An 86-year-old Illinois man with a concealed carry permit fired his weapon at an armed robbery suspect fleeing police last month, stopping the man in his tracks and allowing the police to make an arrest.

Law enforcement authorities described the man as “a model citizen” who “helped others avoid being victims” at an AT&T store outside Chicago where he witnessed the holdup. The man, whose identity was withheld from the press, prevented others from entering the store during the theft.

Police said the robber harassed customers and pistol-whipped one.

Since Illinois started granting concealed carry permits this year, the number of robberies that have led to arrests in Chicago has declined 20 percent from last year, according to police department statistics. Reports of burglary and motor vehicle theft are down 20 percent and 26 percent, respectively. In the first quarter, the city’s homicide rate was at a 56-year low.

“It isn’t any coincidence crime rates started to go down when concealed carry was permitted. Just the idea that the criminals don’t know who’s armed and who isn’t has a deterrence effect,” said Richard Pearson, executive director of the Illinois State Rifle Association. “The police department hasn’t changed a single tactic — they haven’t announced a shift in policy or of course — and yet you have these incredible numbers.”

As of July 29 the state had 83,183 applications for concealed carry and had issued 68,549 licenses. By the end of the year, Mr. Pearson estimates, 100,000 Illinois citizens will be packing. When Illinois began processing requests in January, gun training and shooting classes — which are required for the application — were filling up before the rifle association was able to schedule them, Mr. Pearson said.

“The temperature would be 40 below, and you’d have these guys out on the range, having to crack off the ice from their guns to see the target,” Mr. Pearson said. “But they’d do it, because they were that passionate about getting their license.”

The demand has slowed this summer, but Mr. Pearson expects the state to issue about 300,000 concealed carry permits when all is said and done.

Illinois became the 50th state in the nation to issue concealed weapons permits. An individual permit costs about $600 and requires at least 16 hours of classes.

The Chicago Police Department has credited better police work as a reason for the lower crime rates this year. Police Superintendent Garry F. McCarthy noted the confiscation of more than 1,300 illegal guns in the first three months of the year, better police training and “intelligent policing strategies.”

The Chicago Police Department didn’t respond to a request for comment from The Washington Times.

However, the impact of concealed carry can’t be dismissed. Instead of creating more crimes, which many gun control advocates warn, increased concealed carry rates have coincided with lower rates of crime.

A July study by the Crime Prevention Research Center found that 11.1 million Americans have permits to carry concealed weapons, a 147 percent increase from 4.5 million seven years ago. Meanwhile, homicide and other violent crime rates have dropped by 22 percent.

“There’s a lot of academic research that’s been done on this, and if you look at the peer-reviewed studies, the bottom line is a large majority find a benefit of concealed carry on crime rates — and, at worst, there’s no cost,” said John Lott Jr., president of the Crime Prevention Research Center based in Swarthmore, Pennsylvania. “You can deter criminals with longer prison sentences and penalties, but arming people with the right to defend themselves with a gun is also a deterrence.”

Within Illinois, Cook County, which encompasses Chicago, has the state’s largest number of concealed carry applications, with 28,552 requests, according to the county’s website. Accounting for population, however, less than 1 percent are carrying.

Mason County has the top per-capita rate in Illinois, with 14 percent of its residents holding concealed carry licenses, followed by Shelby County, with 9 percent.

“When I talk to folks that are supporters of concealed carry here, a lot of them want to get their permits so they can keep a gun in the car just so they have it when they travel to bigger towns and cities,” said Shelby County Sheriff Michael Miller.

Shelby County is in southwestern Illinois, about an hour and 45 minutes driving time from St. Louis. Its crime rate is low, and the majority of charges are domestic-related, Sheriff Miller said. He doesn’t anticipate concealed carry to change the statistics much.

“These are folks who just want to exercise their Second Amendment rights,” Sheriff Miller said. “Luckily, we don’t have a gang problem or any serious violent crime. Our types are just rednecks that like to hunt and fish.”

Mason County Sheriff Paul Gann said it’s too early to tell whether an increased carry rate will have an influence on crime rates.

“What I can tell you is we haven’t seen a spike in crime,” said Mr. Gann. “We haven’t seen a spike in anything that’s gun-related — brandishing a firearm, shootings, robberies, nothing. These are law-abiding individuals.”

From a national perspective, Florida has the most active concealed carry permits, at nearly 1.3 million. Texas is second, with just over 708,000. Hawaii, at 183, has the fewest of states whose data were available.

At 300,000 concealed carry licenses, Illinois would compare with Virginia, which has 363,274, and Alabama, with 379,917.